If she was in the adoption kennel for a while, she could easily have packed on weight there. There can also be a variation in scales at vet offices. At my old vet's, Turbo consistently weighed 80+, but any other place I weighed him (the Banfield scale at Pestmart, his Physical Therapist's Office, the weight scales at Wonderland and Raynham), he comes in around 76 lbs (just where I want him - 5lbs over race weight).
According to the records, she was spayed on 4/2/02 and weighed 69 pounds. I got her on 5/16/02. When she was spayed she was still up in Connecticut. But in looking over her records, she's never weighed less than 69 pounds since I've had her. Oh, and she actually gets a bit less to eat than the other two. But she is a big girl... more of her to love